This invention relates to optical receivers for light modulated for data transmission.
Currently there are two ways commonly employed for utilizing light as a carrier for data transmission. For long distances, glass fiber conductors are being used, for example in a fiber distributed digital interface (FDDI) system. For short distances, light radiation is transmitted by a transmitter, and detected by a photosensitive component such as a photodiode. With this arrangement, only a very small portion of the radiated light energy reaches the photosensitive component. To alleviate this problem, the light transmitter may be relatively strong or the light could be focused on the receiver.
U.S. Pat. No. 4,764,984 discloses an optical receiver which effects an alternative way of alleviating the above problem. This known optical receiver, adapted for detecting a time modulated infrared light signal of a preselected wavelength includes a light collecting member made of a transparent core material, containing a fluorescent light absorbing dye molecularly dispersed in the core. A filter is provided for passing light of the preselected wavelength to the light collecting member. A photodiode sensor is operatively associated with the light collecting member for detecting fluorescent light emitted by the collecting member upon exposure to infrared radiation of the preselected wavelength. Since the light collecting member has a surface area much greater than the surface area of the photodiode sensor, a high gain is achieved. However, this known device has the disadvantage of being of cumbersome construction, resulting from the use of a separate filter in association with the light collecting member.